The present invention relates to a transition duct assembly comprising a plurality of transition ducts. Each transition duct has a tubular main body, a flange portion provided at a downstream end of the tubular main body, and a plurality of seals for sealing gaps present between flange portions of neighboring transition ducts. Each seal is received in two opposing receiving channels formed in side edges of the flange portions.
Transition duct assemblies are known in the field of gas turbine engines. A conventional gas turbine engine comprises a compressor, a combustor having several combustor units, a turbine and a transition duct assembly, wherein the transition ducts fluidically connect the single combustor units with the turbine. During the operation of a gas turbine engine, the compressor feeds compressed ambient air to the combustor units. In the combustor units the compressed air is combined with a fuel, whereupon the created mixture is ignited. The combustion products form a working gas, which is routed from the combustor units towards the turbine via the transition ducts. In the turbine the working gas drives rotating blades coupled to a shaft in order to transform the inner energy of the working gas into mechanical energy.
In order to achieve a high degree of efficiency, it is important to avoid or minimize the leakage of compressed air within the gas turbine engine, because such leakages can negatively affect the combustion as well as the required cooling of the gas turbine engine. In particular, it should be prevented that compressed air, which is present in the space surrounding the combustor units, leaks towards the turbine. Due to the high temperature difference present between these engine parts, such a leakage leads to stimulation of undesired oscillations, which may significantly reduce the lifetime of gas turbine engine components, in particular the lifetime of the rotating blades of the turbine.
In order to prevent such a leakage of compressed air towards the turbine, it is already known to provide seals sealing the gaps present between flange portions of neighboring transition ducts. Such seals are normally received in two opposing receiving channels formed in side edges of said flange portions. For example FIGS. 4 and 5 show a known seal 100, which is made of a elongate straight steel strip having a square cross section and a thickness of about 3 mm, wherein the steel strip comprises a riffled surface 101 on one side. The seal 100 seals a gap 102 present between two flange portions 103, each seal being arranged at a downstream end of a tubular main body 104 of a corresponding transition duct 105, which is not shown in further detail. More precisely, the seal 100 is received in two opposing receiving channels 106 formed in side edges 107 of the flange portions 103. The width of the receiving channels 106 is chosen much wider than the thickness of the seal 100, such that the seal 100 is received with large clearance. Accordingly, the seal 100 can freely move within the receiving channels 106 in order to prevent jamming during the operation of the gas turbine engine. However, the wear of the known seal 100 is very high. Accordingly a frequent replacement of such seals 100 is necessary.